Maternal cardiac function in complicated twin pregnancy: a longitudinal study.

Objective: To evaluate longitudinally a cohort of twin pregnancies and to assess whether the occurrence of adverse pregnancy outcome may be related to specific maternal cardiac findings.

Methods: Women with twin pregnancies were enrolled prospectively and underwent serial maternal echocardiography at 20-23 weeks, 26-29 weeks and 30-33 weeks of gestation. Patients were excluded if delivery took place prior to 34 weeks. Cardiac findings were compared between patients with uneventful pregnancy outcome and those who developed one of the following complications: pre-eclampsia or gestational hypertension; small-for-gestational age (SGA) neonates (birth weight of one or both twins < 5(th) centile for gestational age).

Results: A group of 28 twin gestations was obtained for analysis, including eight complicated cases. At each visit, mean ± SD cardiac output (CO) was significantly higher in uncomplicated than complicated twin pregnancies (6.55 ± 0.82 vs 4.99 ± 0.67 L/min, P < 0.001 at 20-23 weeks; 7.31 ± 0.74 vs 5.66 ± 1.17 L/min, P < 0.001 at 26-29 weeks; 7.50 ± 0.89 vs 5.32 ± 0.74 L/min, P < 0.001 at 30-33 weeks), as was stroke volume (83.4 ± 12.2 vs 64.5 ± 9.2 mL, P = 0.001 at 20-23 weeks; 84.4 ± 15.6 vs 64.5 ± 12.0 mL, P = 0.003 at 26-29 weeks; 85.0 ± 19.2 vs 65.6 ± 10.7 mL, P = 0.013 at 30-33 weeks), whereas total vascular resistance (TVR) was lower (1005 ± 137 vs 1406 ± 159 dynes × s/cm(5) , P < 0.001 at 20-23 weeks; 924 ± 100 vs 1249 ± 231 dynes × s/cm(5) , P < 0.001 at 26-29 weeks; 929 ± 96 vs 1400 ± 244 dynes × s/cm(5) , P < 0.001 at 30-33 weeks). Moreover, CO, blood pressure (BP), heart rate (HR) and TVR remained stable throughout the assessed pregnancy interval in women developing a complication, whereas significant changes (rise in CO, HR and BP; fall in TVR) were noted in the uncomplicated group.

Conclusions: Maternal cardiac function in twin pregnancies complicated by pre-eclampsia or SGA neonates apparently does not undergo the profound longitudinal changes that occur in uneventful twin pregnancies.